Transition Metal Crosslinking of Acid-Containing Polymers

ABSTRACT

An acid-functional polymer is reacted with a transition metal compound having an average particle size small enough to react with the polymer at a temperature below the glass transition temperature of the polymer, e.g., at room temperature, to produce cross-linked polymer. The process produces a liquid polymer product that dries to a cross-linked film without the required presence of volatile ligands. Improved coatings such as floor polishes that can be formed from these cross-linked polymers are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority as a divisional of U.S. Non-Provisionalapplication Ser. No. 12/186,627, filed Aug. 6, 2008, which claimspriority from U.S. Provisional Application Ser. No. 60/954,457, filedAug. 7, 2007, each of which are expressly incorporated herein byreference in their entirety.

FIELD OF THE INVENTION

The present invention relates to coating compositions formed of acidcontaining polymer dispersions cross-linked with transitional metalcompounds that form a liquid polymer product capable of drying to form across-linked polymer film.

BACKGROUND OF THE INVENTION

It has been known in the art to add stable complex salts of transitionmetals such as zinc to emulsions and dispersions of acid containingpolymers, such as in U.S. Pat. Nos. 3,308,078; 3,328,325; 3,467,610;3,554,790; 4,150,005; and 4,517,330, which are each incorporated hereinby reference in their entireties.

In practicing this chemistry, complex salts are formed from simple saltor oxides of transition metals with amines or other simple complexingligands.

Since each of the steps in the formation of the complex from the free(or hydrated) metal ion is reversible and runs to equilibrium, theprocess must be forced to completion (tetradentate ligand complex) bymass action, charging an excess of the ligand species. The complexingagent must be a simple ligand, to avoid the formation of very stablecomplex structures that will not donate metals to the acidic polymer.The metal complex is formed before addition to the polymer to increasethe ion complex surface area, decreasing the charge per unit area, sothat the acid containing polymer is stable in the presence of themultivalent ion. The instability of acid containing polymers tomultivalent ions is well known and, in fact, they be are commonly usedto flocculate and precipitate polymers from waste streams (Fe++, Fe+++and Al+++ salts are most commonly used). The reduced charge density ofthe complex multivalent salt provides only minimal disruption of thepolar double layer thought to be responsible for polymer emulsionstability.

When the complex salt solution is added to the acidic emulsion polymer,the salt undergoes counterion exchange. Most commonly, the complexmultivalent cations are prepared as carbonate, bicarbonate, or acetatesalts. As this technology is generally understood, the only limitationof the anion of the salt is that it be a stronger base than the anion ofthe pendant polymeric acid. If weaker base anions, such as chloride,etc., are used as the salt, crosslinking apparently does not occurbecause the process of counterion exchange does not happen; the weakerbase anions do not displace the anion of the polymeric acid.

The conjugate acid of the anion of the stable metal complex must beeither volatile or unstable. For instance, acetic acid, the conjugateacid of acetate anion, is volatile, and carbonic acid, the conjugateacid of both bicarbonate and carbonate anions, is unstable(spontaneously decomposing to carbon dioxide and water). In practice,the evolution of volatile conjugate acid, or the volatile by-products ofthe decomposition of the unstable conjugate acid is a processing problemencountered during this crosslinking reaction.

The complex cation, in close association with polymer carboxylate anionsprovides latent crosslinking of the polymer (Maintenance ChemicalSpecialties, by Walter J. Hackett. Chemical Publishing Co., Inc. N.Y.,1972. pp. 9-13). This crosslinking has been referred to as latentbecause it occurs only after the volatile (amine) ligand is releasedfrom the metal during the polymer film formation stages.

The latent crosslinking may be due to the formation of insolublemetal-polymeric carboxylate salts, or the formation of polymericcarboxyl complexes with the metals.

Complexed transition metal salt latent crosslinking has thus enabled theart to produce polymers that will crosslink in a coating upon drying,without interfering with the film formation process. Since the finalcross-linked polymer effectively has the pendant acid functionality tiedup in insoluble acid-metal salts or complexes, metal cross-linkedpolymers have improved resistance to alkaline materials, such asdetergents or cleaning solutions.

The addition of low levels (typically 1 to 3%) of ammonia or other amineto a cleaner solution is believed to effectively reverse thecrosslinking process. The free metal-amine complex is re-formed, thusfreeing the polymeric acid functionality which may then be attacked bysimple alkaline materials. These amine-containing cleaner solutions areknown as strippers, since they effectively allow for the removal of thepreviously cross-linked films.

One problem of this chemistry has been that application of multiplecoats of compositions containing these metal salt complexes cansometimes prove difficult because the new wet coat of polymercomposition contains a high concentration of the complexing amineligand. This high concentration of free amine, and the amine ligandreleased from the complex, act as a stripper on the previously appliedunder-coat causing redispersion of the under-coat, drag in theapplication of the top coat, whitening and ghosting of the coating, andgeneral disruption of the recoating process known as poor recoatability.These difficulties are particularly noted when coating formulations areapplied rapidly, as is common practice in industrial applications.

Though transition metal salt latent crosslinking of acid-containingemulsion polymers has provided many improvements in dry film properties,the high ammonia content of transition metal complex formulations isdisadvantageous in that it is mildly toxic and highly odoriferous. Thevolatile ligands lead to difficulties in handling, formulating, and useof the emulsion polymers produced by this technology.

In other prior art which achieves a partial solution to this problem,e.g., U.S. Pat. Nos. 5,149,745 and 5,319,018, each of which areexpressly incorporated by reference herein in their entirety, a polymercomposition of this type is formed by heating the polymer dispersion toa temperature above the glass transition temperature of the polymer andmaintaining that temperature as a low or ammonia free metalcross-linking agent is added to the dispersion. However, it is necessaryto heat the dispersion to a temperature above the glass transitiontemperature for the polymer to achieve the desired cross-linking of thepolymer. In these references, it is also disclosed that if the metalcompound is added in finely divided form the reaction will proceed morerapidly. Pre-dispersing the finely divided metal compound will producean even more rapid reaction. But, generally the extent or effectivenessof the reaction is not changed by these modifications, only the speed ofthe reaction.

As a result, it is desirable to develop a transition metal cross-linkingcomposition that is effective in cross-linking polymers, but without theneed for heating the polymer and the cross-linking composition totemperatures exceeding the glass transition temperatures of the polymerin order to achieve the desired levels of cross-linking.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a composition forproducing a cross-linked polymer film is provided that can be formed atroom temperatures, without the need for any addition heat to be added tothe composition. The composition is formed by combining anacid-functional polymer with a transition metal compound having anaverage particle size sufficiently small to be able to react with thepolymer at a temperature below the glass transition temperature (T_(g))of the polymer. The small size of the particles of the transition metalcompound allows the reaction with the acid-functional polymer to takeplace at the temperatures below the glass transition temperature of thepolymer, such as at room temperature, that do not require much if anyadditional energy to be supplied to the transition metalcompound/polymer mixture. During the reaction, the transition metalcompound particles are maintained in contact with the polymer for a timesufficient to allow the reaction to occur.

According to another aspect of the present invention, the films producedfrom the polymer compositions produced according to the inventionexhibit the advantages of the cross-linked, detergent resistant filmsproduced through latent metal salt crosslinking without the toxicity,odor, or application problems associated with the use of volatileligands, such as amines, that have previously been employed incrosslinking acid-containing polymers. Moreover, the process of theinvention appears to produce a more complete crosslinking of the acidfunctionality of the polymer than latent metal salt crosslinking asindicated by the ability to produce higher stoichiometric levels ofreaction with the acid functionality of the polymer when practicing theinvention.

Numerous other aspects, features and advantages of the present inventionwill be made apparent from the following detailed description.

DETAILED DESCRIPTION OF THE INVENTION I. Polymers

Polymeric materials must meet two criteria to be useful in thisinvention. They must be dissolved or dispersed in water and must containpendant acid functionality. Polymers that contain acid functionalityonly as termini or end groups do not produce the desired cross-linkedpolymer and film properties.

The acid functionality may be incorporated in the polymer by known meansusing an effective amount, preferably from 4 to 90% by weight of thetotal monomers of acidic monomers. Examples of acidic monomers areethylenically unsaturated acid monomers, such as acrylic acid,methacrylic acid, maleic acid, itaconic acid, maleic anhydride, vinylphenol and mixtures thereof.

Other monomers in the polymer preparation are selected to produce thedesired end use and application properties sought and include thepolymerizable comonomers which form soft polymers in the presence offree radical catalysts and those that produce hard polymers in thepresence of free radical catalysts. Examples of comonomers whichpolymerize to form soft polymers include primary and secondary alkylacrylate, with alkyl substituents up to eighteen or more carbon atoms,primary or secondary alkyl methacrylates with alkyl substituents of fiveto eighteen or more carbon atoms, or other ethylenically-unsaturatedcompounds which are polymerizable with free radical catalysts to formsoft solid polymers, including vinyl esters of saturated monocarboxylicacids of more than two carbon atoms. The preferred ethylenicallyunsaturated compounds are the stated acrylates, itaconates, andmethacrylates, and of these the most preferred esters are those withalkyl groups of not more than 8 carbon atoms.

The preferred monomers which by themselves yield soft polymers may besummarized by the formula H2C═CR′—CO—O—R^(x), wherein R′ is hydrogen ora methyl group and, when R′ is methyl R^(x) represents a primary orsecondary alkyl group of 5 to 18 carbon atoms, and when R′ is hydrogen,R^(x) represents an alkyl group of not over 18 carbon atoms, preferablyof 2 to 8 carbon atoms and more preferably 2 to 4 carbon atoms.

Typical compounds that can be used in the present invention are ethylacrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, isobutylacrylate, sec-butyl acrylate, amyl acrylate, isoamyl acrylate, hexylacrylate, 2-ethylhexyl acrylate, octyl acrylate,3,5,5-trimethylhexylacrylate, decyl acrylate, dodecyl acrylate, cetylacrylate, octadecyl acrylate, octadecenyl acrylate, n-amyl methacrylate,sec-amyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate,2-ethylbutyl methacrylate, octyl methacrylate, 3,5,5-trimethylhexylmethacrylate, decyl methacrylate, dodecyl methacrylate, octadecylmethacrylate, and those with substituted alkyl groups such asbutoxylethyl acrylate or methacrylate.

Another group of monomers which by themselves yield soft polymers arebutadiene, chloroprene, isobutene, and isoprene. These are monomerscommonly used in rubber latices along with a hard monomer also useful inthis invention, such as acrylonitrile, styrene, and other hard monomersas given above. The olefin monomers, particularly ethylene andpropylene, are also suitable soft monomers.

Examples of polymerizable ethylenically unsaturated monomers which bythemselves form hard polymers, are alkyl methacrylates having alkylgroups of not more than four carbon atoms and alkyl acrylates havingalkyl groups of not more than 2 carbon atoms also tert-amylmethacrylate, ter-butyl or tert-amyl acrylate, cyclohexyl, benzyl orisobornyl acrylate or methacrylate, acrylonitrile, or methacrylonitrile,these constituting a preferred group of the compounds forming hardpolymers. Styrene, vinyl chloride, chloride, chlorostyrene, vinylacetate and a-methylstyrene, which also form hard polymers, may be used.

Preferred monomers, which by themselves form hard polymers, may besummarized by the formula H2C═CR′—X, wherein R′ is hydrogen or a methylgroup and wherein X represents one of the groups—CN, phenyl,methylphenyl, and ester-forming groups, —COOR″, wherein R″ is cyclohexylor methyl or ethyl or a tert-alkyl group of four to five carbon atoms,or, when R′ is methyl, an alkyl group of two to four carbon atoms. Sometypical examples of these have already been named. Other specificcompounds are methyl methacrylate, ethyl methacrylate, propylmethacrylate, isopropyl methacrylate, isobutyl methacrylate, n-butylmethacrylate, sec-butyl methacrylate, and tert-butyl methacrylate.Acrylamide and methacrylamide may also be used as hardening componentsof the copolymer.

A further class of polymers of this invention is polymers of the estersof vinyl alcohol such as vinyl formate, vinyl acetate, vinyl propionate,vinyl butyrate and vinyl versitate. Preferred is poly(vinyl acetate) andcopolymers of vinyl acetate with one or more of the following monomers:vinyl chloride, vinylidene chloride, styrene, vinyl toluene,acrylonitrile, methacrylonitrile, acrylate or methacrylate esters, andthe functional group containing monomers given above.

These polymers can be prepared, for example by emulsion copolymerizationof the several monomers in the proper proportions. Conventional emulsionpolymerization techniques are described in U.S. Pat. Nos. 2,754,280 and2,795,564. Thus the monomers may be emulsified with an anionic, acationic, or a nonionic dispersing agent, about 0.5% to 10% thereofbeing used on the weight of total monomers. When water-soluble monomersare used, the dispersing agent serves to emulsify the other, lesssoluble monomers. A polymerization initiator of the free radical type,such as ammonium or potassium persulfate, may be used alone or inconjunction with an accelerator, such as potassium metabisulfite, orsodium thiosulfate. The initiator and accelerator, commonly referred toas catalyst, may be used in proportions of ½ to 2% each based on theweight of monomers to be copolymerized. The polymerization temperaturemay be from room temperature to 90.degree. C. or more as isconventional.

Examples of emulsifiers or soaps suited to this polymerization processinclude alkali metal and ammonium salts of alkyl, aryl, alkaryl, andaralkyl sulfonates, sulfates, and polyether sulfates; the correspondingphosphates and phosphonates; and ethoxylated fatty acids, alcohols,amines, amides, and alkyl phenols.

Chain transfer agents, including mercaptans, polymercaptans, andpolyhalogen compounds, are often desirable in the polymerization mix.

Staged or sequential copolymers can also be cross-linked according tothe invention. Particularly useful first stage copolymers areethylene/ethylacrylate copolymers and ethylene/vinyl acetate copolymerscontaining added hydrophilic monomer.

For the formation of various products from the polymers that arecross-linked using the transition metal compounds of the presentinvention, such as floor finishes, a particularly preferred class orclasses of polymers are formed from acid functional styrene/acryliccopolymers which have a range of glass transition temperatures fromabout 100° F. to 200° F.

II. Metals

All of the transition metals are capable of forming polymericcrosslinks, though care must be exercised when considering the use ofarsenic, mercury, cobalt, copper, lead, cadmium, nickel and chromium fora specific application due to high cost, toxicity, or the production ofa color in the polymeric film. Certain transition metals such asaluminum, tungsten, and tin that could not be used in latent metal saltcrosslinking because of their inability to form a stable amine complex,are useful in the present invention. Combinations of transition metalsmay be effectively used. The divalent alkaline metals are generally noteffective as crosslinking agents.

Regardless of the particular transition metal compound that is used, theessential aspect of the compound is that the average particle size ofthe compound be sufficiently small to enable the transition metalcompound to react with the polymer at a temperature at or below theT_(g) of the polymer, and optionally without any additional heatrequired to be applied to the composition including the polymer and thetransition metal compound, i.e., at room temperature. This is in directopposition to the findings in the U.S. Pat. No. 5,149,745 and U.S. Pat.No. 5,319,018 patents where no observed reactions between the transitionmetal compounds and the polymers took place at temperatures below theglass transition temperature of the polymers. To achieve these reactionsat the low temperatures not previously though or observed to bepossible, the average particle size for the particles of the transitionmetal compound is preferably less than 300 nm, more preferably less than150 nm and most preferably less than 100 nm. Due to the very smallparticle size, the reaction between the polymer dispersion and thetransition metal compound can occur at temperatures less than the T_(g)of the polymer, such as at or below room temperature. The reason forthis is that the small particle size for the transition metal compoundcan intermix freely within the polymer dispersion without the need forthe input of any external energy, such as by heating the dispersion.Thus, the ability of the transition metal compound to readily intermixwith the polymer negates the need for any additional energy input toinitiate the reaction between the transition metal compound and theacid-functional group on the polymers,

The preferred metals, based on criteria of low cost, low toxicity, andlow color in the cross-linked film, include zinc, aluminum, tin,tungsten and zirconium. Zinc and aluminum are particularly preferred.Useful compounds of the transition metals include the oxide, hydroxide,carbonate and acetate forms of the transition metals, and usually thebasic acetate form of these transition metals.

Non-water soluble transition metal salts are preferably utilized. Thisis because, when used in emulsion or dispersions of acid-containingpolymer, the metal compounds must be relatively insoluble since evenmoderately soluble salts (i.e. ≧0.4% in water at 60.degree. C.) canproduce excessively high levels of multivalent cations in solution. Highlevels of multivalent cations can cause dispersions or emulsions ofacid-containing polymer to precipitate or sediment from the dispersionor emulsion because of the polymer's multivalent cation instability (thedouble layer is believed to be disrupted by multivalent cations). Thisrequirement for a low solubility transition metal compound does notapply to acid-containing polymers in aqueous solution, but only toaqueous dispersions and emulsions of acid-containing polymers.

III. Reaction with Transition Metal Compound

In one embodiment, the process of the invention is practiced by charginga reaction zone with an acid-containing polymer in dispersion orsolution, which can be formed of any suitable organic solvent, but ispreferably water, and charging to this, while the polymer is below theglass transition temperature of the polymer, an appropriate amount oftransition metal compound. As stated previously, this transition metalcompound is formed to have a particle size that is able to react withthe polymer at or below the glass transition temperature of the polymer,and preferably less than 300 nanometers (nm), more preferably less than150 nm, and most preferably less than 100 nm. The compound is maintainedin contact with the acid-containing polymer, at or below the glasstransition temperature, until the reaction is completed. The point ofcompletion of the reaction is indicated by an observable reduction inopacity and an increase in the pH of the reaction mixture. The reactionzone can be any suitable reaction vessel or area in a reactor. Thetransfer of materials from one vessel or portion of a reactor, ifperformed during the reaction, will bring the additional vessel or areaunder the team reaction zone. The process may be practiced as a batch,continuous or semi-continuous process.

The maximum amount of transition metal compound for use in dispersion oremulsion system can be determined by reference to the amount(equivalence) of pendant acid functionally in the polymer and thenselecting the desired amount of metal based on the known valence of themetal ion. Divalent metal ions will stoichiometrically react with twoequivalents of acid per mole of metal salt, and trivalent metal ionswill react with three equivalents of acid. Monovalent metal salts willnot effectively crosslink the polymer by this technique.

It is generally desirable to use less than a full stoichiometricequivalent of the metal to reduce the chance of accidentally chargingmore of the metal than the reaction will consume. The presence of anunreacted excess could decrease the emulsion stability or produce aresidue of metal compound in the resulting film which is undesired insome uses of the reaction product.

If the acid-containing polymer is prepared as an aqueous solutionpolymer with moderate to low solubility it is beneficial to add thetransition metal compound in the form of particles of the transitionmetal compound that are less than 300 nanometers (nm), more preferablyless than 150 nm, and most preferably less than 100 nm in size or as anaqueous dispersion including the transition metal particles of thissize. Doing so avoids the result in which the particles of metalcompound are coated with a layer of insoluble polymeric metal salt whichcan effectively retard further reaction of the polymer with thetransition metal compound particles.

Water insoluble acid-containing polymer dispersions must be maintainedin the acid form before addition of the insoluble metal compound.Partial neutralization of the polymer (2-20%) may be carried out toimpart polymer emulsion stability or polymer solubility, but moreextensive neutralization (for example ≧50%) retards the speed of thereaction of polymer with metal compound.

Water soluble acid-containing polymers must be neutralized to an extentsufficient to maintain their water solubility during reaction with themetal compounds. Polymers of low solubility will require a higher degreeof neutralization to maintain solubility during the reaction, and thoseof higher solubility will require a lesser degree of neutralization.However, the higher the degree of neutralization of the polymeric acidfunctionality, the slower will be the reaction with the transition metalcompound.

In some uses of the polymer product of the invention, such as floorpolish vehicles, it is necessary that the polymer emulsion have a pHgreater than 7.0 so that it will allow other formulation ingredients,such as anionic fluorocarbon surfactant wetting agents, to function intheir intended manner. It is preferred that this pH adjustment be madeafter the polymer emulsion has been reacted with the insoluble metalcompound so that the majority of the polymeric acid functionalityremains in the acid form and the rate of the reaction is notsignificantly slowed. In some applications of emulsion polymer productit is desirable to neutralize the polymer or formulation with a volatilebase, such as ammonia or other amine. It is preferred that any suchbasification be carried out after the polymer has been reacted with theinsoluble transition metal compound. The invention can provide morehighly cross-linked polymers and formulations which are stabilized byneutralization with base but exhibit a much lower pH than is possiblewith amine-complex crosslinking. The mixed metal crosslinking technologydisclosed in U.S. Pat. No. 4,517,330 may be practiced along with theprocess of the invention. It is most desirable to practice thistechnology by adding the basic alkali metal salt after the polymer hasbeen reacted with the transition metal compound, in order to provideacceptable reaction rates. A fraction of the basic alkaline metal saltmay be used to prebasify a small percentage of the polymeric acidfunctionality to provide enhanced polymer stability during the reaction,as has been described above.

After completion of the reaction, in those reactions where a transitionmetal compound has been utilized that has a larger average particlesize, any precipitate that has formed within the final polymercomposition can then be filtered from the composition, to enable thefinal cross-linked polymer composition to be put to its intended use.

The polymer products of the invention are suitable for multiplepurposes, and are particularly suited to uses that must exhibitresistance to chemical or physical challenges. These uses includecoatings such as paints, polishes, particularly floor polishes,industrial and maintenance coatings.

The following examples are provided to further illustrate the practiceof aspects of the invention. These examples should not be read aslimiting the scope of the invention which is described in thespecification and claims. Unless otherwise stated parts are parts byweight and percentages are percentages by weight.

Example 1 Reaction with 50% of Theoretical Stoichiometry of Zinc OxideBased on Polymer Acid Functionality Monomer Mixture Preparation

A suitable monomer mixture for use in forming the acid-functionalpolymer used to form the liquid polymer products of the presentinvention is prepared in a suitable mixing vessel by combining themonomers shown in Table 1:

TABLE 1 Weight Percent Weight of Total Monomer (grams) Monomer Mixturebutyl acrylate (BA) 85.5 22.8 styrene 111.6 29.7 methacrylic acid (MAA)37.5 10.0 methyl methacrylate 140.7 37.5 (MMA)

Polymer Preparation

To form this monomer mixture into the acid-functional polymer, in asuitable reaction vessel equipped with a thermometer, condenser, andstirrer, a solution of 580 grams of deionized (DI) water, 15.0 grams ofa 60% SLES sodium lauryl ether sulfate (SLES) solution and 6.0 grams ofa secondary alcohol (C12-15) ethoxylate (3 moles) is formed in thevessel and heated to 150° F. Next, 20% of the above monomer mixture isadded to the reaction vessel followed by an ammonia persulfate (APS)initiator solution formed as 3 grams DI water per 1 gram APS. Thetemperature of the vessel is then allowed to increase as a result of theexothermic reaction to 175°-180° F. When the exothermic reaction hasceased, as indicated by the plateauing of the temperature within thereaction vessel, the remaining 80% of the monomer mixture is feed intothe reaction vessel at a rate of 5.0 grams per minute. Thepolymerization reaction temperature within the vessel is maintained at175°-180° F. Once the feed is completed, hold the vessel temperature foran additional 1 hour to ensure complete conversion.

Cross-Linked Polymer Formulation Method 1

To 100 grams of the uncross-linked polymer prepared according to theabove procedure, with a composition of 22.8% BA, 29.7% Styrene, 37.5%MA, and 10% MMA, 1.8 grams of a 50% solids dispersion of zinc oxide(ZnO) having a 60 nanometer particle size in water was added. The amountof the ZnO in the dispersion added was approximately equal to one-halfof the stoichiometric amount of ZnO required to react with all of theacid-functional groups present on the polymer utilized. The mixture wasstirred for 1 hour at room temperature, e.g., between about 65° F. toabout 85° F., or more preferably between about 70° F. to about 80° F.,without the addition of any additional energy to the mixture. Theresulting polymer opacity was unchanged and was free of sediment.

Cross-Linked Polymer Formulation Method 2

To 100 grams of the uncross-linked polymer prepared according to theabove procedure, with a composition of 22.8% BA, 29.7% styrene, 37.5%MMA, and 10% MAA, 1.8 grams of a 50% solids slurry of powdered ZnO wasadded which has an average particle size of 300-400 nm. Again, theamount of the ZnO in the dispersion added was approximately equal toone-half of the stoichiometric amount of ZnO required to react with allof the acid-functional groups present on the polymer utilized. Themixture was stirred for 1 hour at room temperature without the additionof any additional energy to the mixture. The resulting polymer increasedin opacity and after standing, heavy sediment developed.

The polymers formulated by methods 1 and 2 above can be utilized toformed any number of various film-forming products, and in particularcan be subsequently utilized in creation of the following concentratedfloor finish/polish formulations. Prior to creating the floor finish,the cross-linked polymer formulated in the second method was filtered toremove the heavy sediment created by the larger ZnO particles used inits formulation.

Floor Finish Ingredients 40% solids Polymer (Methods 1 and 2) 59.6 grams44% solids Alkali Soluble Resin 3.4 grams Ammonium Hydroxide (adjust pHto 7.9-8.4) 0.5 grams Zonyl ™ FSO 0.1 grams Tributoxy ethyl phosphate4.5 grams 40% solids polypropylene wax emulsion 6.4 grams Pre-Mix A:24.5 grams Water 16.3 grams dipropylene glycol monomethyl ether (DPM)4.9 grams diethylene glycol monopropyl ether (DP) 3.3 grams Pre-Mix B:1.0 grams Tego ® Foamex ™ 815-N 0.1 grams Water 0.9 grams

To form the floor polish/finish concentrate, the polymer formed byeither method 1 o 2 described above is placed within a suitable mixingvessel. The alkali soluble resin is then added to the polymer mixturewhile the polymer mixture is agitated. Subsequently, the ammoniumhydroxide is added to the mixture under vigorous stirring, and whilemonitoring the pH of the mixture, in order to adjust the pH of themixture to between 7.9-8.4. Separately from these step, a Pre-Mix A isformed by mixing water, DPM and DP in the above amounts with oneanother. The Pre-Mix A is then added to the polymer mixture drop-wisewhile the polymer mixture is being stirred. The polymer mixtureincluding the Pre-Mix A is then agitated for 30 minutes.

A Pre-Mix B is also prepared by mixing water with Foamex™ 815-N, whichis added in its entirety to the polymer mixture after the 30 minutes ofcontinuous stirring. Subsequently, the tributoxy ethyl phosphate isadded to the mixture in a drop-wise manner, which is then agitatedcontinuously for 30 minutes. The propylene wax emulsion and the Zonyl™FSO are then added sequentially to the mixture under stirring, and theresulting mixture is allowed to stir for one hour to form the floorfinish composition.

The concentrated floor finish composition resulting from the combinationof these components has a Polymer/ASP/Wax ratio of 85/5/10, and a %solids by weight of 32%. The resulting concentrated floor finishesformed with the polymer of method 1 and the polymer of method 2 werethen reduced in solids to 22% with water.

To evaluate the properties of the polymer compositions formed in thesemethods with the transition material compounds having the various sizes,four coats of the two polishes were applied at a rate of ˜1000 squarefeet per gallon to separate black vinyl tiles. Each coat was allowed todry 30 minutes prior to the next coat being applied. After each coat wasapplied the 60 and 20 degree gloss was measured using ASTM D523, withthe results for the testing shown in Table 2.

TABLE 2 Method 1 Polymer Method 2 Polymer Gloss measurement 20 degree 60degree 20 degree 60 degree 2^(nd) Coat 26.7 63.3 14.1 45.6 3^(rd) Coat48.5 79.4 25.3 61.8 4^(th) Coat 57.2 82.3 42.1 71.7 Recoatability/Excellent Poor Redispersion (No ghosting (Ghosting and or whitening)Whitening)The above data demonstrates that the polymer formed with the zinc oxideparticles less than 300 nanometers (nm), more preferably less than 150nm, and most preferably less than 100 nm in size is unexpectedlycross-linking the acid functional groups of the polymer at the reducedreaction temperatures capable as a result of the small transition metalparticle size as seen by the higher gloss reading and the excellentrecoat properties.

Example 2 Comparison Study of the Average Particle Size of the ZnONano-Size Particles and the Rate of Reaction Monomer Mixture Preparation

A suitable monomer mixture for use in forming the acid-functionalpolymer used to form the liquid polymer products of the presentinvention is prepared in a suitable mixing vessel by combining themonomers in Table 3:

TABLE 3 Weight Percent Weight of Total Monomer (grams) Monomer Mixturebutyl acrylate 108.0 30.0 styrene 94.2 26.0 methacrylic acid 54.0 15.0methyl methacrylate 103.8 29.0

Polymer Preparation

To form the above monomer mixture into the desired acid-functionalpolymer, in a suitable reaction vessel equipped with a thermometer,condenser, and stirrer, a solution of 613.3 grams of deionized (DI)water, 14.4 grams of a 60% nonylphenol ethoxylte sulfate (NPES) ammoniasalt solution, and 6.0 grams of a secondary alcohol (C12-15) ethoxylate(3 moles) is formed in the vessel and heated to 150° F. Next, 20% of theabove monomer mixture is added to the reaction vessel, followed by anammonia persulfate (APS) initiator solution formed as 3 grams DI waterper 1 gram APS. The temperature of the vessel is then allowed toincrease as a result of the exothermic reaction to 175°-180° F. When theexothermic reaction has ceased, as indicated by the plateauing of thetemperature within the reaction vessel, the remaining 80% of the monomermixture is feed into the reaction vessel at a rate of 5.0 grams perminute. The polymerization reaction temperature within the vessel ismaintained at 175°-180° F. Once the feed is completed, hold the vesseltemperature for an additional 1 hour to ensure complete conversion.

Cross-Linked Polymer Formulation

To 100 grams of the uncross-linked, acid-functional polymer preparedaccording to the above procedure, with a composition of 30.0% BA, 26.0%styrene, 15.0% MAA, and 29.0% MMA, 2.6 grams of a 50% solids dispersionof ZnO in water were added. Three separate dispersions were formed andeach was added to separate 100 gram aliquots of the acid-functionalpolymer, the dispersions having ZnO particles present therein in 20, 40and 60 nanometer particle sizes, respectively. The amount of the ZnO inthe dispersion added was approximately equal to one-half of thestoichiometric amount of ZnO required to react with all of theacid-functional groups present on the polymer utilized. Each mixture ofthe polymer and the particular ZnO dispersion was stirred for 1 hour atroom temperature without the addition of any additional energy to themixture.

Also, the pH of the mixture was continuously monitored to determine thelength of time required for the pH of the mixture to stabilize, whichprovides evidence that the cross-linking reaction between the ZnOparticles and the acid groups on the polymer to cross-link the polymerhas ceased. For the purposes of this test, the time the pH of themixture stabilized at 6.5 was noted along with the appearance of theliquid polymer, the results of which are shown in Table 4.

TABLE 4 ZnO Average Particle Size 20 nanometers 40 nanometers 60nanometers Time to stabilize 8 minutes 16 minutes 49 minutes at pH = 6.5Appearance Opacity Opacity Opacity unchanged unchanged unchanged Free ofFree of Free of sediment sediment sediment

The above data indicates that the rate of the cross-linking reactionbetween the ZnO and the acid functional groups on the polymer is afunction of the average particle size of the ZnO particle.

Various additional embodiments and alternatives for the composition andmethod of the present invention are contemplated as being within thescope of the following claims particularly pointing out and distinctlyclaiming the subject matter regarded as the invention.

1. A composition comprising the product of the reaction in an aqueoussystem of: (a) a polymer prepared from more than one unsaturatedmonomer, the polymer including from about 4 to about 90 weight percentof acid-functional monomer(s), said polymer having a calculated glasstransition temperature less than the decomposition temperature of thepolymer, with (b) a transition metal compound having an average particlesize sufficiently small to react with the polymer at a temperatureapproximately equal to or below the glass transition temperature of saidpolymer for a time sufficient to produce a degree of reaction of saidacid and metal, wherein said reaction product is capable of forming afilm.
 2. The composition of claim 1, wherein the transition metal isselected from the group consisting of zinc, aluminum, tin, tungsten andzirconium.
 3. The composition of claim 1, wherein the transition metalcompound is an oxide, hydroxide carbonate or acetate.
 4. The compositionof claim 1 further comprising pigments, fillers wetting, emulsifying,buffering and dispersing agents.
 5. A composition comprising the productof the reaction in an aqueous system of: (a) a polymer prepared frommore than one unsaturated monomer, the polymer including from about 4 toabout 90 weight percent of acid-functional monomer(s), said polymerhaving a calculated glass transition temperature less than thedecomposition temperature of the polymer, with (b) a transition metalcompound having an average particle size sufficiently small to reactwith the polymer at a temperature approximately equal to or below theglass transition temperature of said polymer for a time sufficient toproduce a degree of reaction of said acid and metal, wherein saidreaction product is capable of forming a film, wherein the transitionmetal compound has an average particle size less than 300 nm.
 6. Thecomposition of claim 5 wherein the transition metal compound has anaverage particle size of up to 100 nm.
 7. The composition of claim 1wherein the polymer is an acid-functional styrene/acrylic copolymer. 8.The composition of claim 1 wherein the glass transition temperature ofthe polymer is above room temperature, and wherein the transition metalcompound reacts with the polymer at approximately room temperature. 9.The composition of claim 8 wherein the transition metal compound reactswith the polymer below room temperature.
 10. The composition of claim 1,wherein the polymer is an aqueous emulsion or dispersion and thetransition metal compound is insoluble in water.
 11. The composition ofclaim 11 wherein the transition metal compound is in the form of anaqueous dispersion.